1. Field of the Invention
This invention relates to a cassette accommodating a long test film, which contains a reagent giving rise to a change in optical density by a reaction with a liquid sample such as urine or blood, for use in a biochemical analysis apparatus for quantitatively determining chemical constituents or physical constituents contained in the liquid sample. This invention also relates to a system for loading the test film cassette.
2. Description of the Prior Art
Qualitative or quantitative analysis of a specific chemical constituent in a liquid sample is generally conducted for various industrial purposes. Particularly, it is very important in biochemical and clinical fields to quantitatively analyze chemical constituents or physical constituents in body fluid such as blood or urine.
In recent years, as disclosed in, for example, Japanese Patent Publication No. 53(1978)-21677 and Japanese Unexamined Patent Publication No. 55(1980)-164356, there has been developed and put into practice a dry type chemical analysis slide for quantitatively analyzing a specific chemical constituent or a specific physical constituent contained in a liquid sample simply by applying a droplet of the liquid sample. With the chemical analysis slide, it is possible to analyze a liquid sample more simply and more quickly than with the conventional wet type analysis method. Therefore, the use of the chemical analysis slide is desirable particularly in medical organizations, research laboratories, or the like where many samples are to be analyzed.
In order to analyze a chemical constituent or the like contained in a liquid sample by use of the chemical analysis slide, a measured amount of the liquid sample is put on the chemical analysis slide and is maintained at a predetermined temperature (i.e. incubated) for a predetermined time in an incubator to cause a color reaction. The chemical analysis slide is then exposed to measuring light having a wavelength selected in advance in accordance with the combination of the constituent of the liquid sample with a reagent contained in the reagent layer of the chemical analysis slide, and the light reflected by the chemical analysis slide is measured in terms of the optical density. In this manner, it is possible to achieve quantitative analysis of the chemical constituent or the like.
In the medical organizations, research laboratories or the like in which many liquid samples are to be analyzed, it is desirable that the analysis be conducted automatically and sequentially. To satisfy this need, there have been proposed various chemical analysis apparatuses for carrying out sample analysis automatically and sequentially by use of the aforesaid chemical analysis slides. One of such chemical analysis apparatuses is disclosed in, for example, Japanese Unexamined Patent Publication No. 56(1981)-77746. Also, as a means for analyzing liquid samples automatically and sequentially, there has been proposed in, for example, U.S. Pat. No. 3,526,480 an apparatus wherein a long tape-like test film containing a reagent is accommodated instead of the aforesaid chemical analysis slides, and sample application, incubation and measurement are carried out sequentially by pulling out the test film.
With the technique wherein a single chemical analysis slide is used for a single measurement, many chemical analysis slides must be processed for automatically and sequentially carrying out the analysis of liquid samples, and therefore the apparatus becomes complicated, large and expensive. On the other hand, with the technique wherein the long tape-like test film is used, though the measurement can be carried out automatically and sequentially, the long test film is stained by the hands of the operator contacting the long test film at the time the long test film is accommodated in the apparatus, and an error arises with the measurement results. Also, at the time the long test film on which the liquid samples have been applied and which has been used for the measurement is taken out of the apparatus, the hands of the operator contact the long test film and is stained by the liquid samples. On the other hand, after the long test film is accommodated in the apparatus, the unused portion of the long test film on which no liquid sample has yet been applied must be maintained at a predetermined temperature and humidity. Also, it is necessary for the long test film to be adapted to use in various types of apparatuses having different processing capacity.